The overall aim of the proposal is the application of stochastic ultrasonic tissue characterization techniques to the study of abdominal tissues. An interactive ultrasonic data acquisition and analysis system, incorporating a Diasonics RA-1 real-time scanner, will be employed for studies of phantoms, tissue specimens and patients. Goals include the optimization of algorithms for determining statistical parameters of backscattered ultrasonic waveforms, including measures of amplitude distributions, mean scatterer spacing and attenuation. At least 200 fresh pathologic specimens of abdominal tissues will be scanned in vitro, with subsequent correlation of quantitated histopathologic features with ultrasonic tissue characterization parameters. Preliminary in vivo studies of abdominal tissues will be performed to establish normal ranges of ultrasonic parameters and to assess the reproducibility of their measurement. Extensive in vivo evaluations of patients having diffuse liver disease and lymphoma patients will then be performed as the major clinical studies to be undertaken. The ability of quantitative ultrasonic parameters to evaluate progression or regression of diffuse liver abnormality (particularly fibrosis) will be the major goal of the study of liver disease patients; ultrasonic data will be correlated with quantitated liver biopsy results. An in vivo study of spleens and livers of lymphoma patients, who are to undergo staging laparotomy will be performed, with correlation of ultrasonic and histologi data, to determine whether quantitative ultrasonic techniques may have a role to play in staging lymphoma patients. The ability of the tissue characterization techniques to evaluate focal disease processes in the abdomen will also be assessed. Approximately 500 patients will be examined in these clinical studies; informed consent will be obtained in all cases. Overall, it is planned to lay a rigorous foundation of ultrasonic signal-processing techniques, pathological correlations and clinical studies to permit the rational application of stochastic ultrasonic characterization techniques to the clinical evaluation of abdominal tissues.